Burners which combust gas, such as propane and natural gas, are well known and widely applied. For example, boilers, furnaces, kilns, incinerators, dryers, and food processing equipment all commonly rely upon the heat generated by such combustion for proper operation.
Prior art burner designs have been created to mix a combustible gas with air and provide a spark for the purpose of starting. Extensive attention has been directed to finding proper mixing ratios and to creating apparatus for obtaining such ratios to most efficiently burn the gas while maximizing BTU output.
One known type of burner includes a substantially cylindrical housing provided with an inlet and an outlet. A motor connected to a blower or a fan wheel is typically connected to the inlet to direct air needed for combustion therethrough. A gas supply conduit typically enters the inlet end of the housing as well, and terminates in a gas nozzle short of the housing outlet end. The area of the housing downstream of the nozzle defines a combustion chamber. An ignition source, such as a spark plug or rod, is positioned proximate the gas nozzle and can be energized as needed.
In order to generate a desired airflow through the housing to the combustion chamber to obtain the desired BTU output and flame shape, various flame retention or nozzle plates have been created. Such plates are typically provided transverse to the longitudinal axis of the housing, and are positioned slightly upstream of the nozzle. The plates typically include various aperture designs to direct forced air therethrough. Additionally, the airflow velocity through the housing is typically controlled by a damper. Accordingly, the various aperture designs of the plates in combination with the control of airflow with the damper create desired characteristics in the resulting flame.
The airflow characteristics influence BTU output, flame stability, CO and NOx emissions. BTU output is a measure of the strength of the flame and its resulting heat output, and is a function of, among other things, the amounts of air and gas combined and the ratio at which they are combined. Flame stability relates to the maintainability and controllability of the flame. If the gas/air ratio becomes too rich or too lean, the flame can be lost or can burn inefficiently. CO and NOx emission control is critical in complying with various environmental regulations. If the flame is not suitably confined, shaped, and directed, all three of the foregoing characteristics will be adversely affected.